Ipsec Vpn Configuration - ZyXEL Communications SBG3300 series User Manual

L2TP/IPSec VPN Overview
The Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support
virtual private networks (VPNs). However, it does not provide any encryption or
confidentiality by itself; it relies on an encryption protocol that it passes within the
tunnel to provide privacy. For this reason, L2TP is often implemented along with
IPSec. This is referred to as L2TP/IPSec.
IPSec VPN tunnel is established first and then an L2TP tunnel is built inside it.
When the process is complete, L2TP packets between the endpoints are
encapsulated by IPSec.
Since the L2TP packets themselves are wrapped and hidden within the IPSec
packets, no information about the internal private network can be garnered from the
encrypted packets. Also, it is not necessary to open UDP port 1701 (used for L2TP) on
firewalls between the endpoints, since the inner packets are not acted upon until
after IPSec data has been decrypted and stripped, which only takes place at the
endpoints.

IPSec VPN configuration

This section describes the external interface of the IPSec VPN features.
Users can configure IPSec VPN using either the simple wizard of the web
configuration GUI. The simple IPSec VPN Wizard and management of the IPSec VPN
are described first, followed by the description of the web configuration GUI.
IPSec VPN setup:
1. Go to VPN > IPSec VPN > Modify.